Posture chair



April 24, 1945. w. F. HEROLD 2,374,350

POSTURE CHAIR Filed Oct. l, 1941 5 Sheets-Sheet l plil 24, 1945.` W F, HERQLD 2,374,350

PosTURE lCHAIR Filed oct. 1, 1941 s sheets-sheet 2 .lin

April 24, 1945. W. F. HEROLD 2,374,350

' PosTURE CHAIR v Filed Oct. l, 1941 3 Sheets-Sheet 3 I z @j Z JJ., J4 j I7 Patented Apr. 24, 1945 POSTURE Walter F. Herold, Easton Bassick Company, Br poration .off Connecticut Conntass'ignoxf 4to .The idgenort, Conn., a cox-- Application :october i1, 1941,:seria1 Noi mensa `2.4 Claims. This inventionrelatesl to posture chairs ofthat class `in which the seat is swinging'lymounted as well as'the chair back, there being a variable angle between the back'and the seat. 'As the occupantof thechair takes arecliningposition, the angle `betweenthe'seat andthe back-sup porting part ofthe chair is increased lfrom that which obtains in theso-called Working position.

In previously known chairs ofthis'type, in the conventional tilting y-seat chair, which lis known as the bucket'type, the weight'of a person sitting inthe chair is a Yfactor `of primeimportance'fbecause theztilting action is brought about lprimarily -by shifting lthe center o`f-weightof the personisbody Ybeyond 'the Vdead center. A -given chair has its operation considerably aii'ected by the weight of the occupant, and a chair which will operate 'satisfactorily with a person of given weight` requires adjustment if occupied'by a person lof noticeably greater or less weight.

Experiments have shown Athat in the use of tilting chairs the pushing pressure of the feet on the oor exerted by most persons in moving backward is practically a constant and has a substantially uniform value, and that in any casesuch foot pressures of different persons have veryconsiderably'less variationthan the weight of their bodies. 'It is, therefore, an important object of` the present invention to provide a vposture chair whose movements are caused primarily by foot pressure and other movements of the body and are affected to a'minor vdegree only, if at all, 4by variationin the weight'of the occupant.

Itis also an object to eliminate the weight factor for 4all practical purposes and provide'v a chair action ywhich will function correctly and without the need of adjustment if use'dby persons ldiffering in weight through qulteawide range.

It is also an object Ito provide a chair action in which, 4as the chair backis pushed rearwardly under the pushing action Vof the-feet'on thenoor, the tension supporting the tilting seat will be automatically reduced sothat the tilting seat will follow the movement of the thigh as vthe body goes into a reclining position, the foot pressure which` is used to move the -backrear'wardly being the primarycausel of the dropping ofthe rear portion of the seat'.

Other objects of the invention are to provide maximum comfort for the occupant of the .chair and to furnish a chair iron of the posturetype which is very smooth and silent in operation.

To these Yand-other ends the invention consists in the novel features/and combinations of parts to be hereinafter described and-claimed.

In the accompanying drawings:

"Fig. 1 is la vertical central lsection of a chair embodying my'invention, with certain of the parts broken faway, showing the chair in ltheworliing position;

Fig? 2 lsv-asimilar view1-witho'ertainparts omitted, yshowing the" position `of I the parts whenrr the occupant assumes a `full `reclining position;

- lFig. l-3 is acentral longitudinal view of the chair iron, showing-the -samin la position corresponding to that of Fig. 1;

=Figg 4 4is la stop plan view, with 'certain' parts brc'ikenaway and-'others omitted, ofthe structure o tmustrattatiinf-111m; 3; i

JFig. V5"is-`a-v'iew similar to Fig. 3,v showlng'the parts in-the full reclining posi-tionlof'FiggvZ;

liig. 6 `i'sa -section on line 'B-i-of'Fig 3; :and Figs. ""7, 8, -9 and 1'0 are -`somewhat diagramlmatic"i'fietvs,'as `hereinafter described, illustratling theactiono'f the chair. l

'-In-the'present case vI have -selected for'illustration-an olcechair of the executive posture type,

-in 'whicha supporting-pedestal or' base `carries a screw posit adjustable up and' downy by meanslof anfadjusting-nut, the upperl end ofthe scr'ewpost having-rigidly attached thereto a chair iron, said chai-r iron comprising airameA rigid with thel screw post, a pivoted or hinged element adaptedjto swing infa'verticalplane against -theaction of :resilient counter-balancing `m'eans vand having `spiderarr'ns attached to the vunder portionoffthe 1chair seat,'and a yieldabl'y mounted chair back .adapted to have"asubstantially'upright position when thefchairis inthe so-called working `position. The chair back-is swung back in opposition to` a yielding-"support when theiinerson occupying' the chair assumes a reclining position.y The chair .is also Iprovided with `mear'isf whereby 'the initial angularity of fthe back relatively to the 1 seat 'can beadjusted, an'ditis further provided with'means --wlflerebyfthev heightof the chair' backcan'be ad-y -ljusted Inlthedrawingsgthezsupporting pedestal or base is m-dicated at il, vthe screw post 'at fl z, and :the

iadjustingmut forLthe-screw-post at 13. *The chair seat is indicatedlatflf,Lthe-frame member; rigid lwith 'the upper` endsof rthe screw post, 'at 155; and .fthezpivotedfor hinged member, supporting the chair seat, at I6, said pivoted'fmemberccmprising spiderjarms I lrsecuredtosthe under :portion of the 'chairfseatfandaaspannermember I'Bintercon.- ,-necting fsaid'zspider'larms. The iresilient member counter-fbalancing :the `chair-seat and 'certain l.other partsis generally indicated at Ill/the same .b'e'ing of 'the ycmnstruction i hereinafter more parshaped, having a forwardlyA projecting lower partl 23 and a part 24 which projects upwardly at the The spanner member |'8 front end of part 23. is made from sheet metal in an approximately U- shaped form, having side members pivoted near 5' their lower ends 4by means "of a cross pin 26 to the frame l5. At its upper end, each side piece 25 is rigidly secured as by rivets 21. to the corresponding spider arm I1. The Spanner I8 has at.

its upper part an integral connecting portion 28, but this portion -is not of full width,for a part of it, after cutting, is bent downward, as shown at 29, to present a leaf or panel behind and close to the upwardly projecting part 24 of the frame.

'The part 24 has an aperture 30, and the leaf-29 has an aperture 3|, and through these apertures passes altension rod 32 associated with the resilient member |9 previously mentioned. The tension rod 32 has a T-shaped rear extremity y33, with a beveled edge bearing in small grooves 34 on the rear face of panel 29.

Thepart 24 of the frame is provided at the front with a round flange 35 providing a seat for a rubber biscuit 36 of generally cylindrical shape,

provided with a longitudinal bore receiving with.

clearance a portion of the tension rod. In advance of the biscuit 36 another biscuit 31, generally similar to 36, surrounds the tension rod. In front of the biscuit 31 is a cup-like retaining member 38, by means `of ,which the biscuits can be placed under compression by a nut 39, having an interiorly threaded shank 40 engaging threads 4| on ythe front end portion of the tension rod. Between the shank 40 and the retainer 38 a washer42 isinterposed. The retainer 38 is preferably formed of sheet metal with a slight flange 38a at the rim, but other forms of retainer can be used if desired. Y

The chair back 20,which can be of any appro- .priate form, is supported from beneathbythe height adjusting member 2| previously mentioned, and in this instance the height adjusting member isa sheet metal member bent into a U-shape, havinga rear portion 43 attached as by rivets 44 toa cross member 45 carried at the lower por- 'tion of the chair back. The member 2| is provided at the sides with ribs 4B guided up and down in grooves 41 of the angle adjusting member 22. The height adjusting member can be moved up andvdown relatively to the angle adjusting member 22,and,can be clamped inthe desired adjustment by a clamping device indicated generally at 48, and comprising a cross pin 49 carried by member, 22 and ,engaged by slots 50 in member 2|, said clamping means having a clamping nut 5| adapted to force thesides of member 2| frictionally. againstthe sides' of member 22. The nut 5I has a head 52, by means of which it can be yconveniently manipulated.

The 1 member 22 is preferably made of sheet metal, with its connecting portion at the rear and its free ends toward thefront, and said free ends are` pivoted with respect to .the chair seat structure by means such as a cross pin 53. This cross `pin 53 extends between andismounte'd inthecui) CJD

to broadly as a link element. In this particular case the link element 54 .is made of sheet metal and is bent into substantially U-shaped form, the

free Vends of the U having an upper location in proximity to cross pin 53, and the connecting por.. tion 55 of the U having a lower location, as shown in Fig. 3, for example. In this particular case the side members 56 of the U are of substantially `triangular shape, having narrow upper ends with perforations through which the cross pin 53 passes for pivoting purposes.

, Thelink element 54 and the angle vadjusting member 2,2 are relatively adjustable about the axis ofthe cross pin 53, and they canbe clamped in the desired angular relation to each other by Y means such as a clamping device, generally indicated at 51, this clamping device being preferably of the scissor-slot type described in my Patent No. 2,093,319 of September 14, 1937. The member 54 hasarcuate slots 58, and the member 22 straight slots 59, and through the intersecting slots passes a-bolt 60, arranged as disclosed in said patent,A provided at one end with a clamping nut 6| having aV manipulating head 62. By tightening the nut 6| the side members of element 22 can be clamped against the side members of element 54 in the vdesired angular relation.

At-the forward portion of link member 54 and atlthelower part thereof, said link member has a 'cross .pin 63 passing through perforations in the side walls. The endsof the cross pin 63 pass beyond the side walls, and these ends are utilized for pivoting, a controlling member .64,

here shown` as in the nature of a link, connecting'link` 54 with the resilient means i9. In this particular case the link 54 has forwardly extending side members in the form of bars, the 4rear endportions 66 of which are bent inwardly and perforated to engage the ends of the cross whichfthe tension rod 342 passes with clearance.

What is-termed the working position Vof the chair is ,shown in Figs. 1, 3 and '1. These Views show vthe positions of the parts when the chair .isoccupied and the person ysits up straight or leans forward, as in working at a desk.` It will be seen that in this position the chair back is vertical, or substantially so, so that it can conform tothe persons back andl support it, if the person sits erect, in the desired region between the waist and the shoulder blades. y The height of that portion which makes contact with the back ofthe occupant and which in the present case is indicated at 20a, may be adjusted in the usual way by the adjusting means employed in connection with the height adjustingnmember 2|. The Chair Seat ini this position hasy aversi small rearward and downward inclination. The angle between the chair back andthe chairseat may be-slightly yless than 90, asshown, for example, in Fig. l, but the adjustment permitted by the adjustability of vmember 22, ras Ahereinafter described, will enable the initial angle to be varied within rather wide limits.

Inthis working position of the chair, the rubber biscuits 3S `and l31 are under compression, and the tension rod 32 under tension, produced by the screwing'up of the nut 39 to the requisite extent. Both biscuits are active in supporting the seat and back in a predetermined normal or initial position. It* will be seen that rearward tilting of the chair seat is resisted, owing to the fact that rearward movement of the leaf or panel 29 is resisted by the rubber biscuits, supported against the member 24, which have to be compressed as the tension rod is moved rearwardly by member 29 engaging `its rear end. In this working position of the chair, the chair seat is prevented from tipping any farther forward because of the provision of suitable stops, for. eX- ampley stop lugs 69 on the sides of the spanner member engaging stop projections 70 on the sides of the frame member. One pair of these members 69 and 'I0 is shown in Fig. 4, and it will be noted that another pair is employed at the opposite side of the chair iron. In this working position of the chair, both of the rubber biscuits f are under a substantial amount of compression. The cross member y6l, interposed between them, supports the link member 64 from the front end kin about the position shown in Figs. l, 3 and 7,

and the rear end of said link member 64 is instrumental in supporting the link member 54 in the position shown, and this link member 54 in turn holds the chair back 20 in the position previously 4referred to.

When a person seated in the chair leans back slightly, preparatory to assuming a reclined position, the principal chair parts are moved to the positions shown in Fig. 8. In this and the other diagrammatic views, the chair back is shown in simplified for-m at 2Gb, and the link member 54a, corresponding to 54, is continued integrally at Blib to form a bracket joined to 26". It will be seen that as the person leans back slightly, practically all of the action is confined to the chair back and link- 54a, which latter swings about its upper pivot 53 as its lower pivot 63 is thrust forwardly to a certain degree. This causes link 64 to be thrust forwardly from the rear end, and the result of this is' that biscuit 3l is further compressed, as shown in Fig. 8, whereas biscuit 36 has its compression relieved and is permitted to lengthen.

The effect of the lengthening of the biscuit 36 is ver-y important because this means that the effective tension on the chair seat has been reduced as a result of the rearward movement of the chair back. As the tension on the seat is reduced, biscuit 36 in eifect moving to the right (Fig. 8) and away from its co-acting support 24, the'rear portion of the seat automatically drops y(the seat moving about pivot 26), and the tilting of the seat will occur asa result of the rearward ythrust on the chair back. The tilting seat thus follows the movement of the thigh as the body takes a more reclining position, this being due primarily to the push of the persons feet against the floor which brings about a rearward thrust against the back of the chair.

As the person continues the movement to a reclining position, the parts are moved until they "reach the position shown in Fig. 9, which illustrates the `fullyreclinedposition land'corresponds `to Figs.2 and 5. lItwill'beseen that lin this posi- Icompression than:36. :What has occurred has Vbeen anincrease of the compression xofFig. 8, the increaseof compression of biscuit 31 being (rela- `tively greater asazzresult KVof the forward movement of thelowerrendof'link-5l!av under the lback- 'ward thrust on the'cha-ir back, ythe chair back movingabout pivot 53. vInthis position thelspanner member comes `againsta stop 'H on theframe (Fig. 2) which prevents further rearward movement.

Fig. 10 shows the position of the parts when the occupant ofzthe chair leans forward preparatory to 'returning to the working position. It will be seen that when this occurs the seat remains-stationary, at least for ,a short interval, and that the rst movement whichtakes place is primarily a swinging return movement of the chair back on pivot. 53 resulting fromsome relief of the tension of Fig. 9 and movement of the link-64 in a rearward direction under extension of biscuit 3l. On the other hand there is some increase of compresison of biscuit 36. This increase of compression of biscuit 36 causes anincreased tension to be placed on the tilting seat, `and thus the upward movement of the rear, portion ofthe seat toward the initial position (Fig. 7) is brought about automatically so that the seat follows the body and movesto the initial position primarily because there is less pressure of the-.feet against the floor and therefore a relief of the backward pressure against the chan` back.

It will be seen that the interpivoted parts' 54a and 64 have an actionl similar. to that of a toggle, the toggle being operated by the part 54h swinging on the pivot 53. As the partsare moved from the position of Fig. 7 tothatof Fig. 9, the toggle is extended, the action of which is to thrust forwardly the yoke 61 at its free end. While this is occurring, however, there isa simultaneous generally rearward movement of certain parts due to the movement of thechair seat and the chair back about the seat pivot 26. The pivot 53 is swung bodily downwardly and rearwardly while the chair back ispivoting onA it.

It is important that the tension supporting: the

-rear part of the tilting seat be automatically rethat it be automatically increased on the return movement as a result primarily of the decrease of foot pressure. Because these elfects are produced in a chair. in which the seat is pivoted between its ends so as to be rather evenly balanced 0n its pivot, the weight of the person occupying the chair, which is a much more variable factor :than the foot pressure, is of Amuch less consequenc'e than heretoforeand persons of different .weights within relatively wide limits can use a given chair with satisfactory results without the need of adjustment. Furthermore, the flexible connection existing between the seat and the back makes the chair conform itself more readily to the body than has -been the case with previous posture chairs, and the chair is noticeably .more comfortable and smoother in operation.

It will, of course, be noticed that in the fully reclining position shown in Fig. 9 the angle between thechair back and the chair seatis substantially increased. As the parts move 'from the working position to the full reclining position, the angle is progressively increased. This result is brought about in a very simple and effective manner with the use of a minimum number of parts. It is, of course, understood that the initial angular position of the chair back relatively to the seat can be varied by means of the angle adjusting means previously described, which enables the member 22 to be shifted relatively to the link member 54 on the axis of the cross pin 53.

It is, of course, understood that in the chair illustrated a back, provided at the lower part with a forwardly extending bracket structure, is pivoted by this bracket structure to the spider arms supporting the seat. For all practical purposes the link member 54 is a part of this forwardly extending bracket of the chair back, because in operation the link member 54 and the member 22 are rigidly locked together. The bracket so constituted, and swinging on a pivot such as the cross pin 53, is connected at its front lower part by a link, or a like controlling member, to the resilient support. In this particular case the resilient member comprises two springs in the form of separate bodies of rubber between which the forward end of the link 54 is interposed. As the chair back is swung relatively to pivot 53, the controlling member is shifted, in the manner previously described, to redistribute the stresses in the body of rubber constituting the resilient support as a whole. When the chair back alone is moved, as in the case of Figs. 8 and l0, the effect is to relieve stress in one part of the rubber body and increase stress in another part, this action taking place at a point intermediate the ends of the body. When, on the other hand, the seat moves on its pivot, the rubber body is compressed or released from its forward end through the intermediary of the tension rod acting on the retainer or compression head 38. When both the chair back and the chair seat swing on their pivots (the pivot of the chair back being 53), there is an alteration of compression in the resilient support as a whole and at the same time a redistribution of the stresses in the front and rear portions of the support.

It will be seen that by the invention a posture chair action is provided which will operate satisfactorily withoutadjustment where a given chair structure is used by a relatively large number of diierent individuals. The individuals may differ in weight through quite a wide rangey without adversely aiecting the operation of the chair. As most people exert about the same amount of pressing force against the floor in assuming a reclining position in a posture chair, and as the present posture chair is moved from the Working position to the reclining position, and vice versa, primarily by increasing and decreasing the thrust of the feet, and consequently that of the persons back against the chair back, the present chair structure is admirably suited to the standardization of size of the chair, while at the same time meeting the needs of the purchasing publicl It is also evident that a very comfortable chair is provided because of the structure of the chair action, the flexible yielding or lost-motion connection between the seat and the back adding considerably to the comfort lof the user as compared to a chair in which those parts have a positive or rigid connection between them necessitating a given or predetermined movement of one whenever the other is moved.

While I have shown a preferred embodiment of my improved chair iron, it will be understood that the invention can be embodied in many different forms and that various modifications and changes in the organization of parts and in the details can be made without departing from the principles of the invention or the scope of the claims.

What I claim is:

1. In a posture chair, a tiltable seat and a back pivoted to swing with respect to the seat, balancing means comprising front and rear rubber biscuits which are compressed by the backward tilting of the seat, and an operative connection from said back to said balancing means passing into a space between said biscuits so that it is in contact with both of them and operable to vary their compressive relationship,

2. In a posture chair, a screw post, a frame connected to the upper end of the screw post, a chair seat having a spanner pivoted to said frame, front and rear resilient membersl on a tension rod passing through said frame and spanner adapted to be compressed as the seat is tilted rearwardly, a chair back having a bracket by which it is pivoted to said seat, and a connecting link pivoted to said bracket and having a yoke entering the space between said resilient members.

3. In a posture chair, a pivotally mounted seat, a chair back having a lower forwardly projecting bracket member by which it is pivoted to the seat at the under rear portion of the latter, and a common resilient supporting means operatively connected at one point to the bracket and at another point to the seat to control them so that the back has a certain amount of independent movement and at a next succeeding stage a dependent concurrent movement with the seat.

4. In a posture chair, a pivotally mounted seat, a chair back having a lower forwardly projecting bracket member by which it is pivoted to the seat to swing on an axis at the under rear portion of the latter, and resilient supporting means operatively connected at one point to the bracket and at another point to the seat to control their swing- 7 ing movements, the connection of said means to the seat providing an initial rearward swinging movement of the back independently of the seat when the occupant commences to move from the working position to a reclining position, the seat taking up the swinging movement at a later point in the operation.

5. In a posture chair, a post-supported frame, a chair iron member pivoted thereto comprising spider arms and a Spanner, a chair back having a forwardly projecting bracket at its lower part pivoted to the rear portions of the spider arms, and a common resilient means connected to the bracket at one point and to the Spanner at another point maintaining the seat and the chair back under coordinated resilient control in their swinging movements.

6. In a posture chair, a post-supported frame, a chair iron member pivoted thereto comprising spider arms and a Spanner, resilient means interconnecting the Spanner and the frame for resiliently supporting the seat, a chair back having a forwardly projecting bracket at its lower part pivoted to the rear portions of the spider arms, and means connected `to the bracket and maintaining the chair back under resilient control of said resilient means in its swinging movements, said last-named means comprising a link connecting said bracket with a portion of said resilient supporting means.

chair iron-member for tilting movement, a chair;

back havingat the lower part a forwardly projecting bracket member; pivoted to the underpor-v tion of; the seat, and resilient supporting means connected, to saidchair iron member and to said bracket member forv controlling their swinging movements, `said last-named means having a tension rodconnected to tli'e chair iron member and having a pressure controlling connecting memberconnectedto the bracket member.

8. In a posture chair, a seat, a chair iron memberl comprising spider arms attached tothe under portion of said seat, a pivot mounting said chair iron member for tilting movement, a resilient supporting member at. the front of theA chair iron, a link pivoted to the rear portions of said spider arms in depending relation, a second link pivoted tov thelower end of the firstA and-extending forf wardly Yto be controlled by said resilient supporting member, and a chair back rigidly supported by said first link.

9. In a vposture chair, a seat, a chair iron member comprising spider arms attached to the under portion of -Said seat, a pivot mounting said chair iron member for tilting movement, a resilient supporting member atthe front ofthe chair iron, a linkzpivoted to the rear portions of said spider arms in -depending relation, a second link pivoted 1 tothe lower: end of the first and extending forwardly to be controlled by said resilient supportingmember, and a chair back rigidly supported by saidfrst link, said chair back being adjustable onan axis coinciding with the upper pivot of said rstdink.

10. In a posture chair, a; seat, a chair iron member comprising spider arms attached to the under portion of said seat, a chair back carrying a height adjusting member at its lower part and an angle adjusting member to which the height adjusting member is clamped in the desired height adjustment, means for pivoting said angle adjusting member to the rear portions of said spider arms, a tilting mounting for said chair iron member, resilient means controlling the tilting movement, and means for connecting said resilient means with said angle adjusting member to control the movements of the chair back.

11. In a posture chair, a seat, a chair iron member comprising spider arms attached to the under portion of said seat. a chair back carrying a height adjusting member at its lower part and an angle adjusting member to which the height adjusting member is clamped in the desired height adjustment, means for pivoting said angle adjusting member to the rear portions of said spider arms, a tilting mounting for said chairiron member, resilient means controlling the tilting movement, and means for connecting said resilient means with said angle adjusting member to control the movements of the chair back, said lastnamed means including a depending link pivoted to the spider arms coincidently with said angle adjusting member.

12. In a posture chair, a seat, a chair iron member comprising spider arms attached to the under portion of said seat, a chair back carrying a height adjusting member at its lower part and an angle adjusting member to which the height adjusting member is clamped in the desired height adjustment, means for pivoting said angle adjusting member to the rear portions of said spider arms, a tilting mounting for said chair iron member, resilient means controlling the tiltwith respect `to their common pivot to vary theangle ofthe chair back. v

13. A posture chair having an erect seating position and a reclined position, said chair comprisingv a tilting seat and-aback pivoted to the seat',` and atcommon resilient means beneath the seat balancing both the'seatand back in their` movementsand connected at one e'nd to one-and at aniintermediate point to theother and pro-- the-angle between the seat and the chair. backf isfincreasecl.-

14. Ina posture chair, apost-supportedframe, av chair iron member pivoted ythereto. comprising spider arms. and aspanner, alchair backhaving. a'forwardlyprojecting bracketat its llower `part pivoted to the rear portions ofthe spider. arms, and a resilient means supported. on the frame having a-connection tothebraoket at one. point and aconnection to the spanner at another4 point, saidrr connection controlling. the seat` and chair` back so that inthe. initial Apart ofthe movement toward areclinedpositionthe back. under direct pressure moves independently of. the seat and thel seat-supporting tension is decreased; after which the backA and seatiswing concurrently.

15.. In a posture Vchair having a. working position-,andareclined position, the combination of a.base,support, atiltinglpivoted'seat swinging on an axis., intermediate its end portions, a. back pivoted to the seat, ,resilient supportingr means for the seat andl back, and means connecting the seat and back with said means so that in passing from the .working position to the reclined position of the chair the back under direct pressure thereon has initial independent swinging movement followed by a movement concurrently with the seat.

16.- In a posture chair, a pivotally mounted seat, a chair back having a pivotal movement about a pivot fixed in relation to the seat so as swing with respect to' the seat, and resilient supporting means operatively connected at one point to the chair back and at another point to the seat to control them so that the back on being pushed rearwardly has an initial independent movement of predetermined amplitude followed by a concurrent movement of back and seat.

17. In a posture chair, a pivotally mounted seat carrying spider arms and a Spanner, a chair back having a forwardly projecting bracket pivoted to the spider arms, and a resilient supporting means common to the seat and back comprising a tension member connected to the Spanner and a control link connected to and operable from the bracket when the pressure against the back is altered for changing the seat-supporting tension.

18. In a posture chair, the combination of a seat, means underneath the seat whereby it is pivoted intermediate of its end portions, relatively stationarily supported spring means for supporting the seat normally in position for erect seating including a spring member, a back mounted on the seat but capable of swinging movement relative thereto, said seat when tilted acting on said spring member from one end of the latter, and means for connecting said back with saidspring means so that it acts von said spring member from the opposite end thereof to cause pressure thereon.

19. In a posture chair, the combination of a seat, a frame to which said seat is pivoted intermediate the end portions of the seat, a back having a forwardly projecting bracket pivoted to the seat having an axis for swinging movement located adjacent the rear end portion offthe seat, spring means associated with said frame vsupporting the seat so that normally it is in position for erect seating, and means including a link connected to the chair back bracket and extending forwardly therefrom for reducing the seat supporting tension of said spring means when rearward pressure is applied to the upper portion of the chair back.

20. In a posture chair, the combination of a post, a stationary frame carried thereby, a chair iron pivoted to said frame comprising spider arms and a Spanner, a seat mounted on the spider arms, spring means under the seat connected to the Spanner for counterbalancing the seat, a chair back having a bracket by which it is pivoted to the rear end portions of the spider arms, and a forwardly extending pressure element connecting a portion of said bracket below the chair back pivot to said spring means at an intermediate point of said spring means so that the chair back is under the control of said spring -means but with a certain amount of lost motion between the back and the seat.

21. In a posture chair, a tiltingv seat, a back pivoted to swing .with respect to the seat, balancing means comprising compression spring elementsfor suporting .theA seat normally in a position for upright seating, a member operable from the lower part of the back, and apressure member operable from said last member when the back is pushed rearwardly to lessen the seat supporting effect of said elements by changing the degree of compression of one of them.

22. In a chair, the combination of a base, a seat tiltably mounted thereon, a back pivoted to the seat, a spring member supported from the base comprising spring sections, means for connecting the seat to said member so that on backward tilting of the seat said sections are compressed, means for relieving the compression of one'spring section, and means for connecting said last named means to said back for operation therefrom.

- 23. In a posture chair, the combination of a seat, means providing a tilting mounting for the seat, a back pivoted to the seat structure adjacent the lower end of the/back, a resilient support ararngedV to be compressed by the rearward tilting movement of the seat, and means including a member projecting forwardly from the back below its pvot and a pressure link operable from said member engaging said resilient support for rcdistributing the stresses of said resilient support to alter the force acting resiliently on the seat.

24. In a posture chair, the combination of a seat, means providing a tilting mounting for said seat, a swinging back pivoted adjacent its lower end to the seat structure, resilient compression means beneath the seat for supporting the same, means through which rearward tilting of the seat compresses said last means, and means connected to the lower end of the back operable by rearward push on the upper end Portion of the back before the seat is rearwardly tilted for reducing the compression of said compression means and thereby lessening the seat supporting effect of said means.

WALTER F. HEROLD. 

